Client–server model is a distributed application structure that partitions tasks or workloads between the providers of a resource or service, called servers, and service requesters, called clients.

Often clients and servers communicate over a computer network on separate hardware, but both client and server may reside in the same system. A server host runs one or more server programs, which share their resources with clients. A client usually does not share any of its resources, but it requests content or service from a server.

Clients, therefore, initiate communication sessions with servers, which await incoming requests. Examples of computer applications that use the client - server model are email, network printing, and the World Wide Web.